The answer totally depends on the industry. For example, the methods of gaining domain knowledge in financial services will be far different from those for the

The answer totally depends on the industry. For example, the methods of gaining domain knowledge in financial services will be far different from those for the construction industry. Some advice I can give that would apply regardless, is to find a co-founder who is an industry domain expert, and preferably has spent his career working with your potential customers. Not only will finding such a partner greatly accelerate your learning of the domain, but it will get you into sales meetings and closing deals. In many industries, if you are a solo-operator and an outsider, you will have trouble even getting into the room. This is especially true if your competition has a domain expert on the team and you do not.